1. Field of the Invention
The invention is directed to an electrographic printer device for printing web-shaped recording media having different web widths with a possible return of the recording medium from the fixing station to the transfer printing station for producing duplex and color printing.
2. Description of the Related Art
A high economic customer benefit and a broad flexibility are increasingly expected of modern electrographic printer systems. Both the effective utilization of materials to be printed as well as the flexible design of the print information thereby play a great part.
Continuously processing (fan fold) paper electrographic printer systems that can print a web-shaped recording medium on one side have prevailed everywhere in the marketplace where high device availability given great printing volume and a broad spectrum of materials to be printed on are required. These printer systems, however, have the disadvantage that it is not possible to change between single-sided and double-sided printing. For the user, this leads both to an economically unfavorable situation as well as running contrary to the contemporary demands made of raw material utilization. Many customer-associated uses that absolutely require two-sided printing (brochures, books, etc.) can thus not be satisfied, especially since electrographic high-performance printers are especially economical when they are operated without interruption insofar as possible.
For producing multi-color printing and printing of the reverse side of the page with electrographic printer devices working with continuous stock. European Patent Publication EP-B1-01 54 695 discloses that two continuous stock printers be operated following one another, whereby the paper printed in the first printer is turned over and is subsequently printed on the second side in the second printer.
The outlay for such device is substantial due to the required, second printer.
The reference, IBM Technical Disclosure Bulletin, Vol. 22, No. 6, November, 1979, pp. 2465-2466, also discloses an electrophotographic printer device for printing web-shaped recording media, with which it is possible to print the recording medium on both sides. To this end, the recording medium is taken from a supply stack, is supplied to a transfer printing station and is provided with toner images on one side. After fixing of the image on the medium, the recording medium is turned over and is again supplied to the transfer printing station. After printing the reverse side of the recording medium with toner images, another fixing step in the fixing station ensues.
This old reference fundamentally describes duplex printing with continuous stock recording media. The proposal, however, never led to a product. Further, the electrographic printer device is only suitable for both-sided printing of the recording medium. Switching between on sided and two sided printing operating modes is not provided.
The reference XEROX DISCLOSURE JOURNAL, Vol. 9, Bo.3, May 1984, Stanford, Conn., U.S.A., pages 201 through 203 describes methods for duplex printing with a web-shaped recording medium using differently constructed electrophotographic printer devices. In a first duplex printing method, a toner image is first applied to a front side of the recording medium and the recording medium together with the toner image is then turned over and, simultaneously with or immediately before the turn-over operation, the toner image is fixed by a first fixing means attached in the region of the turn-over means. A toner image of the reverse side is subsequently applied with the assistance of the transfer printing station, this being then in turn fixed with the assistance of a further fixing means attached at the output side with reference to the printer device. In a second method for producing duplex printing, a toner image of the front side is first applied with the assistance of the transfer printing station. After this, the recording medium is turned over and the application of the toner image of the reverse side ensues. Both toner images are then simultaneously fixed via a fixing station arranged at the output side. In a third method for producing simplex printing or a narrow or double width recording medium, the application of the sole toner image ensues with a transfer printing station that is appropriately adapted in width, whereby the toner image is then fixed via a width-adapted fixing station at the output side.
Switching between the individual operating modes, for example duplex and simplex printing, within a single printer device with corresponding adaptation of the paper conveying means is not provided. A special fixing station structure, moreover, is proposed for every operating mode.
As already set forth at the outset, electrographic printer devices are utilized for operation with web-shaped recording media when a high printing speed in combination with high printing quality is required. Precisely when processing high print volumes such as represented, for example, by accounting documents, statements of account, fee statements and the like, however, it can be beneficial to print, for example, in two colors in order to more clearly identify specific areas of the forms. Multi-colored printing, however, normally involves substantial outlay and reduces the printing speed.